I am looking for the title of an old science fiction movie in which alien took form a cat. think it was grey. There man who helped cat and race to get rocket back space?

The movie you're looking for is "The Cat from Outer Space". It is a 1978 American science fiction comedy film directed by Norman Tokar and starring Ken Berry, Sandy Duncan, Harry Morgan, Roddy McDowall, and McLean Stevenson. The film tells the story of an alien cat who is sent to Earth to retrieve a powerful weapon that has been stolen by a group of criminals. The cat, named Jake, befriends a young boy named Tommy Anderson, who helps him on his mission.